CBLN1 and obesity due to melanocortin 4 receptor deficiency: Ceramide (Cer) is known to participate in the pathogenesis of insulin resistance and other obesity-associated metabolic diseases 24; however, Cers [Cer(d18:0/24:0)+H, Cer(d18:1/24:0)+H, Cer(d18:2/22:0)+H] was increased only in MTS and hyperlipidemia patients when compared to that in patients with other simple metabolic disorders (Figure 2C).